Статья

GRB 071003: Broadband Follow‐up Observations of a Very Bright Gamma‐Ray Burst in a Galactic Halo

D. A. PerleyDepartment of Astronomy, University of California, Berkeley, CA 94720-3411Wenyu LiDepartment of Astronomy, University of California, Berkeley, CA 94720-3411R. ChornockDepartment of Astronomy, University of California, Berkeley, CA 94720-3411J. X. ProchaskaDepartment of Astronomy and Astrophysics, University of California Observatories/Lick Observatory, University of California, Santa Cruz, CA 95064N. ButlerDepartment of Astronomy, University of California, Berkeley, CA 94720-3411P. ChandraDepartment of Astronomy, University of Virginia, Charlottesville, VA 22904L. K. PollackDepartment of Astronomy and Astrophysics, University of California Observatories/Lick Observatory, University of California, Santa Cruz, CA 95064J. S. BloomDepartment of Astronomy, University of California, Berkeley, CA 94720-3411A. V. FilippenkoDepartment of Astronomy, University of California, Berkeley, CA 94720-3411H. SwanUniversity of Michigan, Randall Laboratory of Physics, Ann Arbor, MI 48109-1040F. YuanUniversity of Michigan, Randall Laboratory of Physics, Ann Arbor, MI 48109-1040C. AkerlofUniversity of Michigan, Randall Laboratory of Physics, Ann Arbor, MI 48109-1040Matthew W. AugerDepartment of Physics, University of California, Davis, CA 95616S. B. CenkoDivision of Physics, Mathematics, and Astronomy, MS 105-24, California Institute of Technology, Pasadena, CA 91125Hsiao‐Wen ChenDepartment of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637C. D. FassnachtDepartment of Physics, University of California, Davis, CA 95616D. B. FoxDivision of Physics, Mathematics, and Astronomy, MS 105-24, California Institute of Technology, Pasadena, CA 91125D. A. FrailNational Radio Astronomy Observatory, Socorro, NM 87801Erik M. JohanssonW. M. Keck Observatory, Kamuela, HI 96743Timothy A. McKayUniversity of Michigan, Randall Laboratory of Physics, Ann Arbor, MI 48109-1040D. Le MignantDepartment of Astronomy and Astrophysics, University of California Observatories/Lick Observatory, University of California, Santa Cruz, CA 95064M. ModjazDepartment of Astronomy, University of California, Berkeley, CA 94720-3411W. RujopakarnSteward Observatory, Tucson, AZ 85721R. RusselThe Aerospace Corporation, Los Angeles, CA 90009-29957Mark A. SkinnerThe Boeing Company, Kihei, HI 96753Graeme H. SmithDepartment of Astronomy and Astrophysics, University of California Observatories/Lick Observatory, University of California, Santa Cruz, CA 95064I. A. SmithDepartment of Physics and Astronomy, Rice University, Houston, TX 77251-1892M. A. van DamW. M. Keck Observatory, Kamuela, HI 96743S. A. YostCollege of St. Benedict, St. Joseph, MN 56374

2008en

ABI

Аннотация

The optical afterglow of long-duration GRB 071003 is among the brightest yet to be detected from any GRB, with A ≈ 12 mag in KAIT observations starting 42 s after the GRB trigger, including filtered detections during prompt emission. However, our high-S/N afterglow spectrum displays only extremely weak absorption lines at what we argue is the host redshift of z = 1.60435, in contrast to the three other, much stronger Mg IT absorption systems observed at lower redshifts. Together with Keck adaptive optics observations, which fail to reveal a host galaxy coincident with the burst position, our observations suggest a halo progenitor and offer a cautionary tale about the use of Mg n for GRB redshift determination. We present early- through late-time observations spanning the electro-magnetic spectrum, constrain the connection between the prompt emission and early variations in the light curve (we observe no correlation), and discuss possible origins for an unusual, marked rebrightening that occurs a few hours after the burst: likely either a late-time refreshed shock or a wide-angle secondary jet. Analysis of the late-time afterglow is most consistent with a wind environment, suggesting a massive star progenitor. Together with GRB 070125, this may indicate that a small but significant portion of star formation in the early universe occurred far outside what we consider a normal galactic disk. © 2008. The American Astronomical Society. All rights reserved.

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Идентификаторы

DOI: 10.1086/591961

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Цитирований: 2Использованных источников: 0

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